1. Field of the Invention
The present invention is directed to a method and apparatus for laying a cover on a landfill, and more particularly to a method and apparatus for laying a cover on the landfill, and depositing ballast on the cover.
2. Description of the Related Art
Landfills have become highly regulated in recent years with an emphasis on minimizing their impact to surrounding populations and the environment. Regulatory agencies, like the Environmental Protection Agency of the United States, mandate requirements for landfill design and maintenance in an attempt to minimize the potential for odors, ground water contamination, fires, blowing litter, disease vectors, and vermin infestation. In an attempt to prevent such undesirable occurrences, regulatory agencies have adopted strict restrictions and codes as to the construction and covering of landfills.
Often, new landfills are created with a liner constructed of a polymeric film to cover the bottom of the landfill to prevent water contamination and disease vectors. The liner is used to prevent seepage from the waste stored on top of the liner from entering into the community water table located underground. Most often, the liner is installed by overlapping sections of film laid along the bottom of the recently excavated landfill and heat sealing the sections together to ensure that no liquid seeps through the liner between the panels of film and into the virgin ground underneath the landfill. It is preferred that such a liner have a long life expectancy and not degrade so that the water table may be separated from the landfill for as long as possible. Once the liner and a required minimum soil cover has been deposited over the base of the landfill, waste materials can then be accepted onto the landfill for disposal.
Landfill covers are required by regulatory agencies at the end of every workday and for landfill sections that are to be left inactive for extended periods of time. Regulatory agencies require exposed waste to be covered in order to reduce the effects of fires, odor, vermin, litter, and disease on nearby populations. It is understood that the open face of a landfill is the surface of compacted trash and garbage, a portion of which is enclosed in plastic bags, and other waste, but can also contain tree pieces, cans, small appliances, wood, shingles, building materials of all kinds, dirt, sludge, or any other material permitted in a landfill. Traditionally, soil was used as the primary means of cover and was applied upon deposited waste in amounts governed by how long the section of the landfill is to remain inactive.
Many current regulations require daily coverage of exposed waste with the daily cover including a minimum of six (eight in some locations) inches of soil applied to the landfill workface. Due to the non-homogeneous layout of most landfills, such a layer of soil may actually reach from 12 to 15 inches in height in certain areas in order to ensure that the six inch minimum exists throughout. Careful planning and management must be applied to each landfill installation to ensure that the utility of the available airspace is maximized. For this reason, landfills are preferably filled in sections, rather than all at once. The accepted process for waste material disposal is to section off a portion of the landfill for the day""s fill and to deposit material there, compact throughout the day, and then cover the section at day""s end.
To maximize the effective use of landfill space, the waste is compacted. Compaction is usually performed in two stages, prior to and after waste deposit in the landfill. Compaction prior to delivery at the landfill is usually performed either by the trash collection trucks or at separate compaction or bailing facilities. Generally, household waste, as collected, is between 250 to 300 lb/yd3 in density. Collection trucks are able to further compact this waste to 400-700 lb/yd3 and bailing facilities are capable of compacting waste to levels exceeding 1000 lb/yd3 in density. Once brought to the landfill facility, waste is deposited into a section of landfill and is further compacted by driving compaction equipment over and about the exposed waste.
Examples of the compaction equipment used for this purpose ranges from dedicated compactors, to standard earthmovers and bulldozers. The size, weight, and range of compaction equipment generally corresponds to the size of the landfill installation, with the largest landfills having the most diverse and heaviest equipment. The compaction equipment is used to move and compact waste material within the deposit zone with its attached blade or bucket device. Once the initial placement and compaction is performed, the compaction equipment is then driven over the deposited waste material several times throughout the workday, further compacting the deposited fill waste. The fill is compacted, preferably using an area, trench or ramp method, into an open face which is typically inclined at angle of from 5xc2x0 to 20xc2x0.
Studies have shown that 3 to 4 compaction cycles provide the ideal amount of compaction for any given weight of machine and that increasing the number of compaction cycles beyond 4 typically yields little gain in effective compactions. Once placed and compacted within the landfill, the same ordinary household waste that began at 250-300 lb/yd3 is now stored within the landfill at 600-1500 lb/yd3, with the actual amount of compaction depending on the weight and size of the equipment utilized and the number of compactions.
Because waste storage capacity is a landfill""s most precious commodity, the traditional soil method of covering the waste has become less and less popular in recent years. In response to the recent demands for more efficient usage of landfill space, alternative daily cover, or ADC, systems have been suggested. The primary goal of an ADC is to perform all of the functions of an eight to six inch layer of soil without the drawback of consuming large amounts of landfill capacity. Attempts have been made to cover landfills with removable tarps, but it has been shown that the deployment and retrieval processes are difficult and labor intensive. Nondegradable disposable plastic liners that are designed to be left in place have been proven to take up little landfill space but are considered potentially dangerous because of their tendency to trap methane and other gasses generated by the waste within the layers of the fill.
One ADC that has been widely accepted is the use of a degradable polyolefin film as disclosed in U.S. Pat. Nos. 5,416,133 and 5,565,503, both hereby incorporated herein by reference. The degradable film of polyolefin is desirable as an ADC because it conserves valuable fill capacity and degrades quickly enough (either through chemical, photo, stress, thermal, or biodegradation) to reduce the potential for the buildup of gasses between fill layers. Apparatuses and methods for deploying degradable film is disclosed in U.S. Pat. Nos. 5,536,116 the xe2x80x9c116 patentxe2x80x9d) and 5,620,281 and U.S. patent application Ser. No. 09/510,956, filed Feb. 22, 2000 all hereby incorporated herein by reference.
The apparatus disclosed in the ""116 patent includes a film deployment apparatus that may be disposed on the blade of a tractor or other prime mover. The deployment apparatus is attached to the blade, usually by chains, hooks, or both. The tractor is usually powered by a diesel engine while the blade, which may be lifted and lowered, is operated by hydraulic fluid lines and a conventional electrical system. The required hydraulic and electrical power needed to operate the deployment apparatus may be obtained from the tractor by conventional hydraulic and electrical take-off lines. Alternatively, the power, fuel and hydraulic systems may be self contained on the deployment apparatus. After the deployment apparatus is attached to the blade, it may be lifted off the ground by actuating a hydraulic cylinder. When not used to support the deployment apparatus, the blade is used to push the waste fill into the operating area of the landfill.
The deployment apparatus operates by unrolling a panel or width of film from a roll of film rotatably mounted on the deployment apparatus as the tractor moves over the workface of the landfill. Frequently, below the roll of film is at least one roller which draws the film back and down as it is unrolled from the film roll. The roller draws the film as close to the workface of the landfill as quickly as possible, thus allowing the film to unroll over the exposed workface of the landfill and seal off deposited waste from the elements and scavenging animals. Once a layer of film is deposited, the film is cut, either by hand or automated device, and the tractor is returned to the top of the workface to lay another layer of film adjacent to the first layer with several inches of overlap. This process is repeated until the entire day""s fill is covered.
Because the film that is laid upon the landfill would otherwise be susceptible to being blown away, the deployment apparatus also deposits ballast on the film as it is laid. The ballast can take the form of any solid or semi-solid medium but is preferably soil. The deployment apparatus contains hoppers that are preferably large enough to hold enough ballast to complete the daily cover operation without refilling. Mechanical apparatus direct the ballast out of the hoppers through outlets, where the ballast is deposited onto the desired locations of laid film.
Each layer of film generally is deployed by positioning the tractor at the top of the area to be covered so that the film is deployed as the tractor backs down the face of the landfill. The film is extended outward of the deployment apparatus and positioned under the guide roller. At the start of each pass of film, the ballast distribution mechanism is activated to deposit ballast upon the leading edge of film. The weight of the deposits of ballast is sufficient to hold the leading edge of the film in place while the tractor with attached deployment apparatus is backed down the workface of the landfill. At intervals selected by the operator, which are either accumulated manually or automatically, additional deposits of ballast are made to help secure the film in place atop the workface of the landfill. Additionally, when beginning a pass over the workface, the film can be temporarily attached about the roller in such a fashion that the weight of the first deposit of ballast frees the film from the roller and allows deployment without assistance.
With the film secured in place atop the workface by the ballast, the requirements for an ADC are met using a system that consumes much less landfill space than the traditional soil cover method. Traditional soil cover systems cost landfill operators a large amount of resources in terms of equipment required and effective fill capacity. A traditional soil cover system requires a large amount of soil to be located nearby and more machinery to emplace than a degradable film cover system.
The apparatus ""116 patent is designed for large amounts fill space which must be covered with high frequency. For small landfills, such as those for remote municipalities, a smaller, less expensive apparatus to deploy film and ballast is highly desirable. Because of the lesser amount of waste deposited each day, small-scale fills are typically in a position to benefit even more from ADC systems than their larger counterparts. For such small-scale facilities, the soil cover material represents a higher percentage of the fill capacity than at larger facilities.
The present invention overcomes the deficiencies of the prior art.
The apparatus and method of the present invention enables a landfill operator to deploy a film material from a standard bucket loader to the working surface of a landfill. The apparatus is preferably attached to the bucket assembly of loader and deploys film as the loader is driven over the working surface of the landfill. Periodically, at intervals determined by the operator, the bucket, which contains a ballast material, is manipulated to allow ballast material to drop onto the film and hold the deployed film in place. In a preferred embodiment, the apparatus includes a roll of film mounted on a mandrel between two flanges. Such an apparatus is preferably attached to the bucket device through chains or wire rope in such a manner as to allow full operation of the bucket while the apparatus is attached. The apparatus of the present invention is also capable of spraying a pesticide, deodorant, or any other chemical, to the exposed working surface. If more than one panel is required to cover the work area, it is preferred that adjacent panels, with some overlap, be laid.